Generally, forage harvesters chop crop material, such as grass or maize, into small particles for storage and subsequent feeding to livestock. Conventional harvesters comprise a rotating cutter head with a plurality of knives, which co-operates with a stationary shear bar to cut the crop material fed thereto into small particles and deliver it to discharge mechanism. It is well-known in forage harvesters to provide a blower for receiving chopped forage either directly from the cutter head or from kernel processing rolls or an impeller or other forage moving apparatus located between the cutter head and blower and for delivering the chopped forage to a forage collecting container such as the box of a wagon or truck, for example.
In an attempt to minimise plugging, designers have advantageously located the blower so as to receive the chopped forage in a relatively thin mat flowing along the outer periphery of the cylindrical blower housing where the forage is engaged and accelerated upwardly by blades or paddles extending generally radially from the blower rotor.
An important problem associated with conventional harvester blowers is that the blowers may be seriously damaged when a foreign object enters the blower. Sometimes, during field activities foreign objects can enter the blower area and cause serious damage to the blower rotor and blower housing. This phenomenon is called a ‘blow-up’. Most of the time it starts when a stone or other hard object enters the harvester, in particular the cutter head, and gets stuck between a knife of the rotating cutter drum and it's counter knife or shear bar. This causes the knife to break such that this piece gets stuck between a subsequent knife and counter knife. A chain reaction is the result. Parts that leave the cutter head area are thrown into the blower and can plug the blower by getting stuck between the rotor and the housing of the blower unit. In most cases, this results in a deformation of the shaft on which the blower rotor is mounted and/or in a deformation of the housing and a serious decrease in efficiency of the blower. Presence of foreign objects in the blower may induce considerable material damage and material loss such that deformed rotor and/or housing will have to be removed and replaced, which involves expensive repair costs and which is time-consuming. Furthermore, the blow-up phenomenon also involves serious risks from a security point of view, since the blower can break down during operation.
The present invention aims to provide a solution to the above-mentioned problem. It is therefore, an objective of the present invention to provide a blower showing improved security and wherein repair costs as a consequence of a blow-up phenomenon can be reduced. The present invention provides a solution to the above-mentioned problems by providing a blower unit having an adjustable housing.